Safety cranking device for internal combustion engines



July 16, 1935. v. J. MURAWSKI SAFETY CRANKING DEVICE FOR INTERNAL COMBUSTION ENGINES Filed May 26, 1954 Patented July 16, 1935 SAFETY CRANKING DEVICE FOR INTERNAL COMBUSTION ENGINES Victor J. Murawski, Hannibal, Mo. Application May 26, 1934, Serial No. 727,619

Claims.

This invention relates to internal combustion engines, and, more particularly, to means for manually cranking the same.

The principal object of the invention is the 5 'provisionof new and improved means forautogines by hand, there is always more or less danger matically disengaging the crank from the crank shaft in the event the engine backfires while manually cranking the same.

Another object of the invention is the provision of a new and improved'safety device for preventing injury to the operator in the event "the engine backfires while being cranked and which is .so constructed as to constitute an attachment that may easily and readily be applied to the engine.

A further object of the invention is the provision of a new and improved attachment for internal combustion engines that may be attached to existing structures with modifications therein.

A still further object of theinvention is the provision of new and'improved means for preventing an operator from becoming injured while manually cranking an engine in the event of backfiring, which is simple in construction, efiieient in operation and that is inexpensive to manufacture and easily installed.

Other and further objects and. advantages of the invention will appear from the following description taken in'connection with the accompanying drawing, in which:-

Fig. l is a perspective view of a portion of an internal combustion engine with the radiator removed, for the sake of clearness, andpartsbroken away, showing the crank in position about to be attached to the crank shaft;

Fig. 2 is a front elevation of the engine with parts omitted for the sake of clearness, and with parts broken away;

Fig. 3 is a side elevation of the forward portion of the engine with parts broken away and showing a crank in the act of being applied for cranking the engine; and r Fig. 4 shows an elevation of the crank.

In the cranking of internal combustion enof backfiring. This is principally due to failure on the part of the operator to retard the spark before cranking the engine, or to sufficiently retard said spark. But from whatever cause, the backfiring of the engine during the cranking operation often results in a broken wrist or arm sometimes other serious injuries-to the operator. a

It has been proposed to' employ safety devices of one kind and another. In some, the structure is so complicated as to be too costly to justify their use; others require changes in the engine structure or modifications of the crank shaft,

While still others require a radical departure from 'theconventional. crank mechanism for starting the engine.

The present invention seeks to avoid these Referring now to the drawing, the reference character It) designates an internal combustion, engine, having the gear case I l for the cam shaft gears on the front thereof, as is usual in such constructions. The crank shaft 12 is of the conventional type and extends through the gear case H in the usual manner.

The crank shaft is provided with the usual cranking pin l3, which is adapted to be engaged by shoulders or clutch teeth M on a head l5 of the starting crank I6. In some engines, the crank shaft carries the clutch teeth and the crank carriesthe pin, but it is immaterial how these parts are arranged. Since the parts thus far described are of the usual or well-known construction, it is I not thought necessary to further illustrate or describe the same.

The mechanism for preventing the reverse movement of the crank and for disengaging the shoulders or clutch teeth l 4 from the pin l3 when I I, as by means of rivets or tap screws I9, or other suitable means.

The ratchet member I! is provided on its face with the ratchet teeth 2|. The head ii of the starting crank I6 is provided inwardly of the shoulders It! with an enlargement'ZZ which may be attached thereto or integral therewith. Preferably, though not necessarily, the enlargement 22 may be cast integral with the head l5. It has an annular face 23 extending at right angles to the axis of the head. Pivotally secured in the enlargement 22 and adapted to extend outwardly beyond the annular face 23 of the enlargement are the pawls 24 and 25. These pawls are pivoted in the bottom of recesses 25 formed in the face 23 in any suitable manner, as by means of the pins 21. The rear walls of the recesses 26 are curved, as shown at 28, and the pawls are also curved and substantially conform to the curved wall 28. The outer ends of the pawls 24 and 25 ends rigidly secured in recesses in the head 22 are employed for this purpose. The outer or free ends of the springs 29 are unattached to the pawls, whereby the pawls are free to take the po- 7 sition shown in dotted lines in Fig-3 for disengaging the crank when the engine backfires.

In the operation of the device,- the starting crank is attached to the crank shaft i2,= in the usual manner, with the shoulders or clutch teeth I 4 in'engagementwith the pins! 3..' Uponturning.

thei'crank :for. starting the engine, first one pawl and :thenithe'other will snap past the teeth 2!,

and,.:inthe event the engine backfires, the pawls willtprevent the. backward rotation'oi the crank.

Upon reverse rotation-of the engine crank shaft, engagement of pin is and shoulders I4 causesthe starting crank 18 to rotate reversely an infinitesimal-.amount, or just sufficiently toseat the. free,

'ends1'of the pawls 24 and 25 in the spaces betweeniratchet teeth 2 l. Because the pivot pins 21 of the..:pawls are positioned appreciably behind thaface -23 of the head 22,.and the pawls extend thereforeidiagonally; the rotary impulse given the starting crank by the :reversely rotating engine crank shaft, or; more strictly-speaking, the rotary reaction of. the ratchet member I 1 against the pawl ends; does not act longitudinally of the pawls, but contains two components, a rotative 40c force and an endwise thrust. The pawls therefore pivot on their pins 23,, turning out of the recesses ZbZrand act as levers for pushing the head I5 of the starting crank outwardly from the ratchet member. The length of the pawls and the depth 1:- of the shoulders or cluteh'teeth it are so propor tioned that when the pawls have acted through theirfull capacity to separate the members and I5, the pin i3 is disengaged from the shoulders I4. This mode of operation is made clear in Fig. 3,;where dotted lines'show'one of the pawls in extended position consequent upon reverse rotation of the engine crank shaft, and where the extended pawl is shown projecting beyond the shoulder l4 sufiiciently to assure disengagement f. the pin Hi from the shoulder upon full exten SlOIl/Of'lih pawl.

In order that the device maybe readily ape pliedras an attachment to engines as at present constructed, the ratchet member ll may be provided withdiametrically extending slots 3| and 32 which form a continuation of the axial opening 33.- Itwill only be necessary to drill holes-through the front plate or wall of the gear case in order tosecure the ratchet member in position; or on someengines where the gear case is omitted, it

may be attached directly to the cylinder block or other part of the engine.

In applying the ratchet member I! to the engine, the plate or front wall it or" the gear case H is tapped, after which the member I? is slid onto the crank shaft i2 by turning the same to the position where the slots 3| and 32 are in alignment With'the pin. The ratchet member is then :secured in position by applying the tap "screws- In certain cases the ratchet member is appended."

' extends, a crank having a detachable connection secured in position by rivets. In such cases, the gear case plate must first be removed.

It is thought from the foregoing taken in connection with the accompanying drawing that the construction and operation of my device will be apparent to those skilled in the art, and that changes in size, shape, proportion and details of construction may be made without departing from the. spirit andscope of theclaimshereunto I claim as my invention:-

1..In an internal combustion engine provided with a crank shaft extending outwardly from the engine, a ratchet rigidly secured in position and having anaxial opening through which said shaft with said shaft, and a pawl at opposite sides on said crank pivoted in recesses for engaging the teethpf said ratchet and'adapted to cause the disengagement of said connection upon the backfiringofsaid engine. I a 1 2..A starting crank for internal combustion engines comprising a head having-means for-fle tachably connecting the same to the-crankshaft of an internal combustion engine, an enlargement on said head having an annularfacein' a pla'nenormal to the axis of said headya plurality -01? curved pawls pivotally mounted in recessesinsaid face and resilient meansfor normally projecting the free ends .of said pawls beyond saidfa'cee 3; In an internal combustion engine, an at tachment comprising a ratchet member havirig' openings for receivingthe fasteningmeans for: rigidly attaching thesame to said engineand having an axial opening with diametrically oppo siteslots' extending radiallyfromfsaidfiopemng through which the :crank shaftiof an Tengine having .radially extending studs are adapted Jto extend, and a starting crankhavingclutch teeth for engaging said studs and provided with sprin 40h pressed pawls engaging saidratchet 'teethysaid pawls having their innerends pivoted in recessesin said crank and movable toia positionsto disen gage. said clutch teeth from saidpin;

4. .Anattachment for use on .aninternalz com-1' bustion engine comprising a ratchet memberham-r ing ratchet teeth on one face and providedwithtt means for rigidly attaching the sametcr ammugine, a crank having ,clutchteethiforrturnin'g a; crank shaft of an engine, said crankfhaving zan portion provided with a plurality of IGCESSBSEabOIItI its axis, pawls pivoted in'said :recesses'and slid-.- able over said ratchet teeth WhBII Said'CIaIIKJSEQ movedin one direction and engaging said ratchet: teeth and moving said' crank axially"outwardlywhen moved inthe other direction. I

5.In an internal combustion engine having-a crank shaft. provided at one end withapainptr oppositely arranged radially extendingrpins, their combination of-a starting crank providedwitha I head having clutch teeth for engagingysaid' pins; a ratchet member rigidly secured tosai'd-enginez over said crank shaft and having a'recessafor re-p ceiving said head, an enlargement extending about said head outwardly thereof, said enlarge;- a ment having a plurality of equi-angularlyspacedz recesses in its inner face, springepressed'ipawls pivoted atthe bottom of said recesses, said'pawls adapted to be received within said recesses to pass! over said teeth while cranking the-engine and gm n to project beyond said recesses :for ;disengaging:;.- said starting crank-upon the backfiringiof. 'saide:

engine. i i i r VICTOR J. MURAWSKI; j

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